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RAW Profiling Center

Our consolidated area for all things RAW for LightZone: current and latest RAW profiles, dcraw updating, and instructions for creating RAW profiles for LightZone Updated: June 20, 2013RAW Profiles and D.I.Y. Profiling

Mottling in dark areas in Lightzone on Mac

Posting rules: It shouldn't need saying, but... play nice. Please keep your discussions civil. You can disagree, just don't be disagreeable. And, of course, all of the usual stuff like no spamming. Tex adds: I'll be rigorously enforcing this as we go along. We're probably going to be a small community in a little lifeboat, so we can't have members at each others' throats. This is for the sake of the project as a whole. So when you post, pretend you're speaking in person with your very wealthy auntie who has always treated you wonderfully and currently lists you prominently in her will. I won't be tossing anyone out of the forums because we are all in this together (except spammers: immediate membership cancelation), but I'll delete suspect posts right away.

Dark areas show up noisy and mottled in Lightzone on a Mac, but when viewed with Preview, the tiff files are smoother. The file is a scan of a negative, scanned at about 1200 dpi on an Epson V750 scanner, 16 bit grayscale.

I would attach two screen shots, one of the file in Lightzone, the other in Preview, but I am not permitted to attach files, apparently. Nevertheless, the Preview is 'smoother'.

(Is there a way to attach files?)

The mottling effect gets exaggerated with 'developing' in LightZone, and is transferred to the prints. That is, it is not only a render issue on the screen.

Is there some setting I have wrong that causes this mottling affect in dark areas?

I'm not at home currently and don't have all my tools and toys at hand. I thought, LightZone might not properly support greyscale colour space, but it looks the same with this image, converted to 16-bit rgb.

I'll see, if I can find out something sensible at the end of the week. Other forum members are invited, of course.

I had previously tried converting the grayscale profile from the Epson scanner to Adobe RGB (1998). It seemed to 'brighten' the whites a bit, but the dark areas still had the noise. The noise gets excarbated when processing the picture. My wife has Photoshop on her computer, and she did not see the noise there.

Thank you for taking the time to look at this. I don't know if it is a problem for other people - I'm not sure how many Lightzone readers are scanning (black and white) film.

Interesting. It almost looks like the LightZone is using 8 bits instead of 16 (the Epson scanner 'supposedly' uses 16 bits), but even the Gimp (which I believe is still 8 bit) shows a better gradation. I'm not familiar with the other programs (heard of RawTherapee, but never used it).

which does support 16-bit and more, and will become the stable 2.10 some day, some year.

But the gradation is better also in IrfanView, that is only 8-bit capable.

I remember I have noticed unpleasant transitions from black to (dark) grey also with some raw photos, blaming LightZone's demosaicing algorithm for them. It might be something completely different, like Python would say, but it is out of my humble abilities to diagnose it.